encoded avif could display complete green on some decoders

[qdwang]

20251013_170247-IMG.AVIF.zip

This avif file is encoded by libavif API, it works great on any platform, like browsers, iOS 18, lightroom, macos 15 etc.

But it will show complete green in the Photos App under iOS 26. (Even if the file is in Files App under iOS 26, it displays great)

I know it could be an iOS bug.

But why this sample displays correctly on iOS 26?
sample: https://github.com/AOMediaCodec/av1-avif/blob/main/testFiles/Link-U/fox.profile2.12bpc.yuv444.avif

And I also converted my avif to another yuv444 12bit avif by using magick, it also works great on iOS 26.

By using avifdec -i i cannot get too much useful info to analyze the issue, they are pretty much the same.

I'm wondering what's the flaw in my encoded avif...

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Updated

I figured out avifEncoderAddImageGrid can cause the issue. (Also does avifenc --grid NxN)

[wantehchang]

@leo-barnes Leo: Could you look into this? Thanks.

[leo-barnes]

@leo-barnes Leo: Could you look into this? Thanks.

I can reproduce on iOS. We'll look into it.

[qdwang]

@leo-barnes

--depth 10 or use RGB mode (--cicp X/X/0) can prevent this issue

[qdwang]

@leo-barnes @wantehchang

Can this issue possibly be solved though libavif part? Or it has to be solved in iOS part?

I also submitted a feedback to Apple, the status "Recent Similar Reports" is "More than 10".

[wantehchang]

@qdwang We need more information from the iOS investigation to know if it is possible for AVIF encoders to work around it.

[qdwang]

@wantehchang New test from me

If the avif file is bt2100 hlg, then it displays correctly on iOS 26.

But when you zoom in the photo, it becomes complete black.

I guess it's still an iOS bug...They even mess up with the JPEG XL lossy DNG decoding(also complete black) on iOS 26.1 which worked fine from iOS 17 - iOS 26.0.1

[wantehchang]

Thanks for the new information. I've forwarded it to our collaborator at Apple.

[leo-barnes]

@qdwang

We've identified where the bug is happening and will fix it. The trigger seems to be the combination of 12-bit content and a grid. If you want to work around it until it's resolved you can do either of:

• Encode as 10-bit
• Encode as a single tile rather than grid

[wantehchang]

Leo: Thank you for the reply. Is there an issue number (rdar number) that we can use to refer to this iOS bug?

[qdwang]

@leo-barnes great. Thank you. Hope this can be fixed soon.